1. Field of the Invention
The present invention relates to an exhaust gas cleaning device for internal combustion engines, which is adapted to supply secondary air into an exhaust system to oxidize and remove the unburnt noxious components such as HC, CO and so forth contained in the exhaust gas flowing in the exhaust system.
2. Description of the Prior Art
An exhaust gas cleaning device has been known having a secondary air supply system connected to the exhaust system of an internal combustion engine and provided with a reed valve device adapted to be opened and closed in response to the pulsation of the exhaust gas pressure in the exhaust system, thereby to permit the secondary air to be introduced into the exhaust system to clean the exhaust gas.
This type of exhaust gas cleaning device is required to meet various demands. For instance, it is necessary for the reed valve device to be opened and closed in precise response to the pulsation of the exhaust gas to permit the required amount of secondary air to be introduced into the exhaust system without encountering any substantial resistance to ensure the oxidation of the unburnt substances. It is also required that the reed valve device be mounted in a compact manner on a suitable portion of the internal combustion engine without interfering with the layout and mounting of other equipment. The exhaust system should have a simple construction composed of a small number of parts for easy assembling and also be capable of being produced at a sufficiently low cost. It is further preferred that the exhaust gas cleaning device not adversely affect the appearance of the internal combustion engine when mounted thereon.